Compressor unloader



Aug. 19, 19240 s. B. REDFIELD COMPRESSOR UNLOADER a ield Filed Dec. 6. 1923 2 Sheets-Sheet 2 INVENTOR cfnowdnfi'li'e ATTORNE PELEBR Aug. 19, 1924.

.' I T STATES SNOWDEN B. REDFIELD, 0F EASTON, PENNSYLVANIA, ASSIGNOR TO INGEBSOLL-RAND CO, 0E JERSEY CITY, NEW JERSEY, A. CORPORATION OF NEW JERSEY.

COMPRESSOR UNLOADEB.

Application filed December 6, 1928. Serial No. 678,792.

To all whom it my concern:

Be it known that I, SNOWDEN B. Rnorrnnn, a citizen of the United States, and a resident of Easton, county of Northampton, and State of Pennsylvania, have invented a certain Compressor Unloader, of which the following is a specification, accompanied by drawings.

This invention relates to compressor unloaders but more particularly to unloading mechanism which may be manually or automatically operated to unload the compressor 0 linder so that the compressor ma contmue to be operated without 'accomp ishing useful work, or a reduced amount of useful work.

It is often desirable to start a compressor under a no-load condition especially if the compressor is driven by an electric motor or ifthe discharge line pressure is .high. In accordance with the present invention, means are provided for manual] unloading the compressor cylinder by hol, ing one or more inlet valves-open, so that the fluid drawn into the compressor cylinder on the suction stroke of the compressor piston will be forced out to atmos here on the compression stroke when bot inlet valves are held open, or a reduced amount of pressure fluid forced into the discharge line when one valve is held open. This manual unloading may be accomplished by turning a handle which causes fingers to bear against and unseat the compressor valve.

The present invention also contemplates means whereby the unloading of the compressor may be automatically governed by the receiver pressure, so that when the pressure therein has reached a certain prede termined point partial or complete unloading may automatically occur. 7

One of the objects of the resent inven tion is to enable manual unloading of acompressor to be accomplished by turning or rotating a handle to cause members such as fingers to bear. against anduns'eat a com-- premor valve. v

Another objectof'the inventiom is to produce a compressor unloader adaptedto be either pneumatically or manually pe t d which may be cheaply manufactured and't'fis readily and convenientl applicable F to a compressor in an .assemb ed condition.

,"Stud the hollow boss U and is preferably provided with extensions W, terminating in an A further object of the present invention is to improve upon compressor unloaders with the view ofmaking them more rugged, reduce the number of parts, facilitate their assembly in a compressor cylinder, and effect afluid tight construction.

Further objects will hereinafter appear and the invention consists of. certain combinations of elements and features of con struction particularly set forth in this specification, defined in the appendedclaims, and shown in the accompanying drawings, in which- Figure 1 is a diagrammatic elevation partly in vertical section of a compressor unit,

Figure 2 is an enlarged vertical sectional view of the compressor unloader shown in Fi re 1.

igure 3 is a view similar to Figure 2 showing the compressor valve held open,

Figure 4 is a horizontal sectional view taken onthe line 4-4=--of Figure 3, and

Figure 5 is a horizontal sectional view taken on the line 5--5 of Figure 3 looking in the direction of the arrows.

Referring to the drawings, the compressor A is formed with a casing B and cylinder wall G, in which a piston D having a iston rod E is adaptedto reciprocate, being driven from any suitable source of power. The compressor cylinder wall C is provided with suitable inlet valves F which are in communication with the intake conduit G, and

suitable discharge valves H which in this instance are in communication with a receiver J through the discharge line K. An inlet valve mechanism preferably comprises a valve seat L, and guard 0, between which is clamped a plate valve P, by means of a bolt Q and nutR. It is to be understood,

however, that any suitable valve mechanism may be employed without departing from the scope of the present invention.

In accordance with the present invention, a cover S having a hollow boss U, is preferably securedto the compressor casing B bolts T. A cylinder V is located annular ring W, adapted to bear against the valve seat L for holding the valve mecli! anism in place in the compressor cylinder C.

An external annular flange X is in this instanoe formed on the cylinder V and limits theinward movement of the cylinder in the hollow boss U in the assembly of the parts.

A hollow piston Y preferably having a suitable piston ring Z is slidably mounted in the cylinder V and is in this instance formed with a threaded end portion a, on which is screwed a collar 6. Instead of threading the collar 6, a diagonal slot may be formed therein adapted-to cooperate wit a pin or lug on the end portion a of the cylinder. A plurality of fingers c are preferably formed integrally with the collar b and extend outwardly therefrom -for unseating the compressor valve, as will be hereinafter described. In order to hold the piston Y normally in its inward position, in the cylinder V and to hold the fingers c normally away from the plate valve P, a coil spring-u is in this instance inter osed between the inside of the piston and the valve mechanism F.

Opposed lugs, preferablva pair of In d are in this instance form on one'end o the piston Y, and a stem e is preferably rovided with a cross pin 7, which is adapte to bear against the lugs d. "stem 6, in thisinstance, extends through a plate 9 which is suitably secured to the cover 8 by stud bolts h, and a suitable handle on the stem 6 enables theistem to be readily manipulated. A packing gland 7c and packing o in this instance surround the stem e and serve to prevent the escape of pressure fluid from a chamber 1) which is formed between the late g and'the inner end ,of the piston A suitable packin g is in this instance interosed between t e-plate g, cover S and cylinder V, and pressure fluid is prevented from escaping therebetween by tightening the plate 9 on the cover S. Suitable packings r are preferably interposed between the cover and compressor casin B, and valve seat L and compressor 0 lin er 0, for maintaining a tight 'ointdietween the parts. By constructing t e unloading mechanism as described, considerable flexibility between the parts is obtained and the cover S, plate 9, swimming B can be secured firmly together to efi'ect an efiicient fluid tight connection. This construction makes this device applicable not alone to air com ressors, but to other analogous types of mac ines as an ammonia or other gas compressor.

' In this instance a coil spring a is located between the cross pin f and plate 9 and permits the stem e to move a slight distance inwardly in the plate 9 when the plate is being secured to the cover S, so that breakage of the cross pin f will be prevented in the assembl of the parts. A collar 6' on the stem e imits the inward movement of the stem in the plate 9.

In the operation of the unloader so far described, by turning the handle j to rotate the stem e in a counter-clock-wise direction, with the cross in f bearing against the lugs d, the piston will be unscrewed from the collar 6, because the fingers c are held from rotation by the webs t in the valve seat L,

as indicated in Figure 4. The fingers 0 will accordingly be moved outwardl the threaded end portion a and the 1ston I will press inwardly in the cylinder against the plate g. As the fin ers 0 move outwardly from the cylinder V t ey will bear against and unseat the plate valve P, and the pressure fluid drawn into the compressor cylinder on the suction stroke of the compressor piston D will be forced out to atmosphere upon the compression stroke of the piston when both inlet valvesare 0 on, and no pressure fluid will be forced into the discharge line K. By turning the handle j in a clock-wise direction, the collar 6 will be moved inwardly on the threaded end portion a and the fingers 0 drawn away from the compressor valve P, and the compressor is permitted to reload with the inlet valves operating normally.

' Suitable automatic means is provided for unseating the compressor valve P and in this instance, the plate 9 is provided with a passage '0, which 1s adapted to communicate with a receiver J by suitable piping w. In order to regulate the passage of air from the receiver J to the chamber 1) in rear of the piston-Y, a suitable auxiliary valve 0: is connected to the piping w and is adapted to be adjusted to the pressure desired in the receiver J. As soon as the pressure in the receiver J has reached a desired point, as controlled by the auxiliary valve :0, pressure fluid will be admitted through the piping w to move the piston Y in order that the fin ers a may bear against and; unseat the p ate valve P. As soon as the ressure in the receiver J has drop ed sufll zziently, the auxiliary valve 2; wills ut ofl the assage of fluid from the receiver J to the c amber and the spring-u will return the piston to its normal position, and thereby permit the plate valve P to function normally.

In order to obtain partial unloading, one of the auxiliary valves a may be set to opcrate at one pressure in the receiver and the other auxiliary valve may be set to operate at a higher pressure. In this manner, when the receiver pressure reaches a certain point, one of the auxilia valves will operate to admit pressure flui d to one of the unloaders, but the'other unloader will not be brought into operation, and as a result the comressor will work at onl half load.

urther increase in pressure inthe receiver will'bring the other auxiliary valve into operation, and complete unloading will occur. It is' to be understood that any suitable auxiliary valve may be employed so that air from will be automatically supplied to the unloading device, after the receiver pressure has reached a predetermined point.

I claim:

1. A compressor unloader comprising in combination with'a compressor cylinder and plate valve mechanism in the wall of said cylinder, a cover adapted to be secured to t e compressor cylinder casing, a cylinder in said cover having means for holding the valve mechanism in place in the compressor cylinder, a piston in said last mentioned cylinder having a threaded end portion, a collar on said threaded end-portion pro.- vided with fingers adapted to bear against the plate valve, opposed lugs on one end of the piston, a plate secured to the cover, a

stem extending through said plate and provided with means for engaging said In s, and means for rotating said stem, where y rotation of the stem in one direction causes the fingers to bear against and unseat the plate valve.

2. A compressor unloader comprising in combination with a compressor cy i a plate valve mechanism, a cover adapted to be secured to the compressor cylinder casing, a cylinder in said cover having means for holding the valve mechanism in lace in the compressor cylinder, a piston sli able in said last mentioned cyhnder having a threaded end portion, a collar on said threaded end portion provided with fingers adapted to bear against the plate valve, a spring bearing against the valve mechanism at one end and the inside of the said piston at the opposite end, opposed lugs on the piston at one end thereof, a plate secured to the cover, packing between the plate, cylinder and cover and forming a seal there between, a stem in said plate, and means;

carried by one end of the stem adapted to bear against said in s, and means for rotating said stem where y rotation of the stem in one direction causes the fingers to bear,

against and unseat the plate valve.

3. A compressor unloader com rising in combination with a compressor cy inder and a plate valve mechanism, a cover adapted to be secured to the compressor cylinder casing,'a cylinder in said cover havln extensions terminating in a ring for he ding nder and the valve mechanism in place in the compressor cylinder, a piston slidable in said last mentioned cylinderhaving a threaded end portion, a collar on said threaded end portion provided with fingers adapted to bear against the plate valve, a spring hearing against the valve mechanism at one end and the inside of the said piston at the opposite end, opposed lugs formed on the piston at one end thereof, a plate secured to the cover, packing between the plate, cylinder and cover for preventing the escape of ressure fluid therebetween, a stem extending through said plate, a cross pin carried by one end of the stem adapted to bear against said lugs, means for rotating said the compressor cylinder casing, a cylinder in" said cover having extensions terminating in a ring for holding the valve mechanism 'in place inthe compressor cylinder, a piston slidable in said last mentioned cylinder having a threaded end portion, a collar on said threaded end portion provided with fingers adapted to bear against the plate valve, a

spring bearing against the valve mechanism at one end and the inside of the said piston at the opposite end, opposed 111 s formed on the piston at one end thereo a plate secured to the cover, packing between the plate, cylinder and cover for preventing the escape of pressure fluid therebetween, a stem extending through said plate, a cross pin carried by one end of the stem adapted to bear against said lugs, means forfrotating said stem whereby rotation of the stem in one direction causes the fin ers to bear against and unseat the plate va ve, and auto matic means for pneumatically operating said piston to unseat said plate valve- In testimony whereof I have signed this specification. 

